Food allergy is a clinically unresolved problem among the most widespread diseases in the industrialized countries. About 8% children and 2% adults are estimated to suffer from food allergy. In the western countries the main food allergens derive from eggs, peanuts, milk, fish, fruits and vegetables.
A survey based on a four-year data summary in the United States of America has lead to extrapolate an occurrence of 29.000 cases of anaphylaxis caused by food, with about 150 deaths per year. This value, as related with the European Union population, would indicate the probability of about 200 deaths per year caused by food-induced anaphylactic shock.
It has been noted that the number of individuals suffering from this pathology has increased in recent years. At present, in case of established allergy, eliminating the offensive food from the diet is the only available cure, with all the consequences that this may bring to the individual's nutrition, also considering that small amounts of the offending food may be present in complex food. The contribution by the transformation industry to the research directed to developing hypo- or non-allergenic products has been poor so far.
Particularly, the industrial derivatives of tomato are one of the most manufactured conserves in temperate-climate countries and consumed almost worldwide, being widely used in a considerable number of food preparations.
The currently available industrial derivatives of tomato are already partially hypo-allergenic compared with the fresh product, due to the thermal instability of some allergenic proteins that are present in fresh tomatoes. However, the protein responsible for OAS (LTP) is very stable at high temperatures, therefore it is present in the industrial derivatives of tomato.
The technical problem addressed by the present invention is to provide fruit and vegetable derivatives that are hypo-allergenic mainly because they exhibit either poor or no LTP content, thereby being suitable for those individuals suffering from OAS induced from fruits and vegetables.
This problem is solved by means of a process such as defined in the annexed claims.
In a first aspect, the present invention relates to a process for manufacturing fruit and/or vegetable hypo-allergenic derivatives comprising: (a) separating the serum of said fruits and/or vegetables from pulp; (b) ultrafiltrating the serum, such as a permeate and retentate are obtained, and (c) washing the pulp; (d) adding the permeate to the pulp to obtain the end product which is a fresh hypo-allergenic fruit and/or vegetable derivative.
Separating the serum from the pulp (step (a)) is carried out by means of centrifugation, preferably with a horizontal axis continuous centrifuge of the decanter type. Centrifugation is carried out at a speed ranging between 500 and 12.000 rev/min, preferably between 1000 and 5000 rev/min. Temperature ranges between 5 and 90° C., preferably between 18 and 70° C. Centrifugation is preferably carried out continuously. Subsequent filtration of the serum, step (b), is a ultrafiltration.
Washing the pulp (step (c)) is carried out by means of an acidic solution which is preferably a citric acid solution.
After the permeate has been added to the pulp (step (d)), the hypo-allergenic end product can be either subjected to a homogenization step (e) and a continuous-flow sterilization step (f), and subsequently aseptically packaged, or it can be packaged and subsequently sterilized according to the known technologies. That is to say, preserved and traded in a deep-frozen state.
In a second aspect, the present invention relates to products obtainable from the process described above. Said products are hypo-allergenic industrial derivatives of fresh products such as fruits and/or vegetables, e.g. juices, nectars, jams, puree, concentrates, etc.; preferably they are hypo-allergenic juices, nectars, puree and concentrates of tomato (Lycopersicon esculentum), peach (Prunis persica), apricot (Prunus armeniaca), cherry (Prunus avium and Prunus cerasus), apple (Malus communis), pear (Pyrus communis), carrot (Daucus carota), celery (Apium graveolens), celeriac (Apium graveolens rapaceum). Still more preferably, they are hypo-allergenic juices, nectars, puree and concentrates of tomato.
With the term “hypo-allergenic” has been intended products that may also be non-allergenic. In fact, the protein content in the end product obtained by means of the inventive process may also be considered as null.
Further characteristics and advantages of the process according to the present invention will be better understood from the description below, which is intended to be merely illustrative and non-limiting.
By means of the techniques known to those skilled in the art, the fruit and/or vegetable, following the washing and sorting operations is subjected to crushing or grinding, possibly after destoning, when the stone is present, a thermal treatment, preferably carried out with a cold break process and then sieving with pulpers-refiners provided with sieves having 0.8-1.1 mm and 0.4-0.6 mm holes, respectively; a sieved product of fruit and/or vegetable is thus obtained (step a0).
The sieved product of fruit and/or vegetable having a solid ratio ranging between 1 and 14%, preferably between 3 and 9%, is subjected to centrifugation to give an amount of pulp ranging between 3 and 90%, preferably between 5 and 80% and an amount of serum ranging between 97 and 10%, preferably between 95 and 20%. The amounts of pulp and serum that can be obtained depend on the characteristics of the fruit/vegetable being processed.
Preferably, the said centrifugation is carried out at a speed ranging between 500 and 12.000 rev/min, preferably between 1000 and 5000 rev/min. Temperature will range between 5 and 90° C., preferably between 18 and 70° C. In a preferred embodiment, centrifugation is carried out by a horizontal axis continuous centrifuge of the decanter type.
The serum is subjected to ultrafiltration, thereby obtaining a retentate and a permeate. Said ultrafiltration is carried out with membranes having a cut-off ranging between 3 and 30 kDa, preferably between 5 and 15 kDa. From ultrafiltration there can be obtained 5 to 90% retentate, preferably 10 to 80%, and 95 to 10% permeate, preferably 90 to 20%.
The permeate obtained following ultrafiltration may be optionally concentrated by reverse osmosis with membranes having a sodium chloride retention ranging between 99.9 and 50%, preferably between 80 and 60%. The solid concentration of the reverse osmosis retentate may range between 5 and 45%, preferably between 20 and 35%.
The pulp is washed, i.e. added with an acidic solution and subjected to stirring and accurate mixing. Preferably, said acidic solution is a 0.1-5% citric acid solution, preferably about 1%. The acidified pulp is subjected to centrifugation, preferably at a speed ranging between 500 and 12.000 rev/min, preferably between 1000 and 5000 rev/min. The temperature ranges between 15 and 90° C., preferably between 18 and 70° C. The centrifugation is carried out continuously. Subsequent to centrifugation a washed pulp is obtained. Said washing step is repeated 1-10 times, preferably 2-5 times.
Said washed pulp and said permeate, possibly concentrated by reverse osmosis, are mixed to each other, with 1:0.5 to 1:50 ratio, preferably 1:1 to 1:10, such as to obtain the hypo-allergenic fruit and/or vegetable derivative. Said fruit derivative contains a total solid percentage ranging between 4.5 and 45%, preferably between about 5% and 36%.
Said hypo-allergenic derivative is homogenized, packaged and sterilized according to the technologies known in the field, thereby obtaining an end product that is stable over time.
Said end product may be, for example, either subjected to continuous-flow sterilization and subsequently aseptically packaged, or packaged and subsequently sterilized according to the known technologies.
The process of the present invention provides hypo-allergenic fruit and/or vegetable derivatives. In this way, individuals suffering from OAS who were obliged to eliminate certain food from their daily diet may use these products that are necessary for proper nutrition, nutritionally valid and organoleptically pleasant. Furthermore, they can be usefully taken for general consumption in order to prevent sensitization in atopic patients.
The products obtainable with the method provided herein are hypo-allergenic because they practically do not contain proteins. Proteins are present in the fresh product at a maximum percentage less than 0.5% and their elimination is not significant from the nutritional point of view.
The examples described herein are intended as being merely illustrative and non exhaustive of the process.